CN1412268A

CN1412268A - Nano-grade silicon nitride composite material heating body and its production process

Info

Publication number: CN1412268A
Application number: CN 01136305
Authority: CN
Inventors: 刘庆昌
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-09
Filing date: 2001-10-09
Publication date: 2003-04-23
Anticipated expiration: 2021-10-09
Also published as: CN1204223C

Abstract

The present invention relates to an improvement on silicone nitride heating body, it adopts nano silicone nitride fine powder and adds general silicone nitride powder so as to allain the goal of modification. Said formula adopts 45-82% of silicone nitride whose grain size is 0.1-5 micrometers, 14-40% of silicone silicate micropowder whose grain size is less than 100 nm, and adds 0.1-5% of aluminium oxide and 3.5-10% of yttrium oxide as additive.

Description

Nano-grade silicon nitride composite material heating body and manufacture craft

Technical field

The present invention relates to the electricity is the heating element structure material prescription and the manufacture craft thereof of the energy, particularly with the situation of silicon nitride as the heating element base mateiral.

Technical background

Heating element is applied among the daily living article extremely at large, and powerful heating element also is widely used in industry heating, insulation and heating.Prevailing structure is to do the structure that the heating element outsourcing forms the combined type heating element with copper material behind the nichrome wire outsourcing insulating material, and this structure heating body is because residual a large amount of gases in the insulant, and the oxidation loss of high temperature resistance silk is serious and the life-span is too short.Even the very tight of insulation layer parcel also can't be solved fast, the flimsy disadvantage of oxidation, and the safety performance that works together is too poor.Used though there is the PTC ceramic heating element to make well heater in recent years, but still do not break away from the technological deficiency of life-span weak point, poor stability.99113534.2 number patent disclosure a kind of silicon nitride heat generating body and preparation method thereof.This heating element is sintered into one ceramic raw materials such as resistance wire and silicon nitride and additive and makes the direet-heating type heating element.Can say that this sets up heater structure is a breakthrough greatly, because not only because the high temperature resistant and insulation characterisitic of silicon nitride itself is good, heat conduction is fast, makes indirect type heating element form become the direct type heating element.And because the secluding air source is improved its life-span greatly, safety performance is also improved thereupon.Yet this kind structure still can't be broken away from and remain in air residual in the sintered compact.Still there is residual threat in nichrome wire, and its heat conductivility is still not ideal enough.The too expensive cost that causes of raw material as aluminium nitride raises in addition.It should be noted that especially this proportioning makes the sintering condition of silicon nitride in the complete processing must be at high pressure, high temperature compacted under.Its technological operation complexity, technology difficulty is big, the cost height be that production cost further improves, to such an extent as to have influence on this series products development, popularize.

Summary of the invention

The objective of the invention is further improvement to existing silicon oxide heating element prescription and technology, make it overcome current material cost height, the anti-dissatisfactory defective of loss of heat conduction sealing, make great efforts to make production technique to simplify,, help popularizing and using to reduce cost comprehensively.

Key of the present invention is to add the nano-grade silicon nitride modification and removes expensive aluminium nitride in the component of heating element.Nano level silicon nitride is meant the micro mist material of its granularity less than 100nm.Because nano-grade silicon nitride can strengthen its average surface after adding, it is also easy that the intergranular contact area strengthens, grain boundary area is big, diffusion length is short, dissolving is separated out, so technological temperature and pressure when having reduced its sintering widely, and sintered density is improved, the quality of finished product obviously improves.Again because nano-grade silicon nitride mostly is α-phase Si3N4.Theoretical analysis proves that the crystal grain increase of α-phase helps reducing sintering pressure, realizes normal pressure-sintered silicon nitride moulding, this shortage in prior art just.α-phase nano level ultrafine silica powder add-on too conference causes the bad grasp of shrinkage, does not also meet relatively cheap principle.So the nano-grade silicon nitride that is added is to be no more than 40% for well, then effect is very unobvious very little for its quantity, on a small quantity should be more than 14%.The little part of granularity of common silicon nitride that is adopted also should could guarantee that the silicon nitride composite material of modification shows tangible performance advantage between 0.1～5 μ m.Common silicon nitride consumption is between 45～82%, by experiment the Al that adds 0.1～5% in the silicon nitride base-material of modification ₂O ₃Can improve highly dense sintering effect and good homogeneous grain-size more significantly and improve toughness and intensity with 3.9～10% Y2O3.

Take above component proportioning to come sintering to make silicon nitride heat generating body and can simplify operational process of craft greatly, realize low energy, low consumption, high-quality effect.

By the basic raw material that this component ratio range is made into, take following technology to make finished product:

1, is made into raw material by above-described modification silicon nitride component ratio, raw material is inserted ethanol, the polyvinyl alcohol (or the two equal compound) that adds a small amount of (below 1%) in the high-strength plastic material container, and put the silicon nitride abrading-ball into or the Al2O3 abrading-ball carried out ball milling 4～30 hours, become batch mixing.

2, batch mixing is put into the drying baker of inflated with nitrogen, removed foreign material after the oven dry and form base-material.

3, design the metal die of geometrical dimension by product requirement, base-material is inserted mould, simultaneously nichrome wire is pressed location, space geometry position, extrusion forming behind the matched moulds.

4, the moulding fetus is put into sintering oven, use Si ₃N ₄The powder that buries that+BN+MgO powder is formed buries it, after put into to heat up under the stove inflated with nitrogen condition and be pressurized to 1900 ℃～2100 ℃, pressure 1～5Mp, constant temperature wait 1～3 hour.

5, stop to heat up, imperial pressure back made it temperature in 60～120 minutes and reduces to 600 ℃～800 ℃.

6, after temperature was reduced to 150 ℃, depressurization took out product behind the naturally cooling.

Further specify below in conjunction with embodiment and the objective of the invention is how to realize.

Embodiment: (components by weight percentage) unit: %

Component	????A	????B	????C	????D	????E	????F	????G	????H
Component	????A	????B	????C	????D	????E	????F	????G	????H	Silicon nitride (0.1-0.35 μ m)	????45	????48	????55	????65	????70	????75	????80	????82
Nano-grade silicon nitride (less than 100nm)	????40	????38	????32	????23	????19	????16	????15	????14	Silicon nitride (0.1-0.35 μ m)	????45	????48	????55	????65	????70	????75	????80	????82
Nano-grade silicon nitride (less than 100nm)	????40	????38	????32	????23	????19	????16	????15	????14	Aluminium sesquioxide	????5	????45	????4	????3.5	????3	????2	????1	????0.1
Yttrium oxide	????10	????9.5	????9	????8.5	????8	????7	????4	????3.9	Aluminium sesquioxide	????5	????45	????4	????3.5	????3	????2	????1	????0.1

Embodiment 1:

The special-purpose high strength plastics container of raw material being put into ball mill in the ratio of the prescription A in the table 1 adds the ethanol or the poly-ethanol of 0.5～1% weight, putting into abrading-ball (silicon nitride or alchlor material) back ground 3～40 hours, after putting into drying baker again and under nitrogen atmosphere, drying, insert metal die behind the sieve impurity elimination thing, in the matched moulds process tungsten filament is imbedded mixed resin by design requirements, with 30～50 tons pressing machine extrusion forming.Blank after the moulding is put into sintering oven and is buried back intensification pressurization under nitrogen atmosphere with burying powder.Be warming up to 1500 ℃～1600 ℃ in 30～60 minutes, pressure is enlarged to 1～2Mp, keeps 3～10 minutes follow-up continuing to be warming up to 1800 ℃～1900 ℃, and pressure is enlarged under 2～3Mp, keeps 3～10 minutes.Be warming up to 1900 ℃～2100 ℃ again, pressure reaches 3～5Mp, keeps 1～3 hour.Stop then heating, drive to be pressed in and make temperature drop to 600 ℃～800 ℃ in 60～120 minutes, after continuing then to be cooled to 150 ℃, natural ventilation, be cooled to normal temperature after finished product successfully come out of the stove.

Controllable Temperature is built in 180 ℃～300 ℃ in drying baker, and pressing machine is that 30～50 tons of press are plastic during pressurization.The used proportioning component that buries powder is (ratio of quality and the number of copies):

Si ₃N ₄4～6 parts

3～5 parts of BN

1 part of MgO

Embodiment 2～8 can be according to prescription B～G formulation ratio raw material, and becomes product with reference to the processes of embodiment 1.

By the heating element that above proportioning raw material and complete processing process, heat-up rate is accelerated, and strength high toughness is good, and the life-span improves significantly, and owing to take normal pressure-sintered cost to decline to a great extent, becomes a kind of desirable heating element that universal prospect is arranged.

Claims

1, a kind of silicon nitride heat generating body, it is characterized in that by drawing lead, the nichrome wire that links to each other with lead and forming with the silicon nitride composite material body that nichrome wire is sintered into one the component proportioning of body is (weight percent):

The silicon nitride granularity accounts for 45～82% at 0.1～5 μ m,

Granularity accounts for 14～40% less than 100nm,

Aluminium sesquioxide accounts for 0.1～5%,

Yttrium oxide accounts for 3.9～10%.

2,, it is characterized in that said nichrome wire is a tungsten filament according to claims 1 said silicon nitride heat generating body.

3, according to claims 1 said silicon nitride heat generating body, it is characterized in that the mean particle size of aluminium sesquioxide should be less than 5 μ m, the mean particle size of yttrium oxide is less than 6 μ m.

4, the manufacture craft of silicon nitride heat generating body is characterized in that this technology is by following process operations:

(1) press claims 1 said component than the preparation raw material, raw material is inserted in the high strength plastics container, add a spot of (below 1%) ethanol, polyvinyl alcohol, and put silicon nitride or aluminium sesquioxide abrading-ball into, ball milling 3～40 hours,

(2) batch mixing that ball milling is good is inserted drying baker charging under the nitrogen situation, and screen out foreign material after the oven dry and make base-material,

(3) carry out by the geometrical dimension of product design and will sieve the back base-material behind the metal die and insert, simultaneously nichrome wire press the space geometry position and located, extrusion forming behind the matched moulds,

(4) the moulding fetus is put into sintering oven, use Si ₃N ₄Burying that+BN+MgO forms put into stove after powder buries, and heat up and be pressurized to 1900 ℃～2100 ℃, pressure 1～5Mp, constant temperature kept 1～3 hour,

(5) stop to heat and drive to press, make it temperature in 60～120 minutes and reduce to 600 ℃～800 ℃,

Open fire door when (6) temperature is reduced to 150 ℃, naturally cooling becomes product.

5, according to claims 3 said silicon nitride heat generating body manufacture crafts, it is characterized in that the temperature in drying baker is 180 ℃～300 ℃, the metal die pressurization is 30～50 tons with pressing machine.

6, according to claims 3 said silicon nitride heat generating body manufacture crafts, the component proportioning (weight ratio) that it is characterized in that burying powder:

Si ₃N ₄: BN: MgO is 4～6: 3～5: 1.

7, according to claims 3 said silicon nitride heat generating body manufacture crafts, it is characterized in that heating up in the pressure sintering process, in 30～60 minutes temperature is risen to 1500 ℃～1600 ℃, pressure adds to 1～2Mp, keeps 3～10 minutes, continue to be warming up to 1800 ℃～1900 ℃, pressure adds to 2～3Mp, keeps 3～10 minutes, is warming up to 1900 ℃～2100 ℃ again, pressure reaches 3～5Mp, keeps 1～3 hour.